Certificate to my 3rd Great Grandfather, signed by Abraham Lincoln

From the certificate:
Whereas the President of the United States has made the following Executive Order ordering Thanks to the VOLUNTEERS FOR ONE HUNDRED DAYS, from the States of Indiana, Illinois, Iowa and Wisconsin to wit:.......
Now, therefore, the Certificate of Thanks and of Honorable Service is conferred on Private John Miller, in token of his HAVING HONORABLY SERVED AS A VOLUNTEER FOR ONE HUNDRED DAYS in Company of 135 Regiment of Illinois Volunteer Infantry.
Given under my hand at the City of Washington, this fifteenth day of December in the year of our Lord one thousand eight hundred and sixty-four.
Signed by Abraham Lincoln, Edwin M. Stanton, Secretary of War. The document is also registered and signed by Assistant Adjutant General, E.D. Townsend

John Miller is my 3rd Great Grandfather and this document has been handed down through my family since it was received.

I would like to know if there is a value on this document.